text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
   * Copyright (C) 2015 Linaro Ltd.
   * Author: Jassi Brar <jaswinder.singh@linaro.org>
   */
  
  #include <linux/amba/bus.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/mailbox_controller.h>
  #include <linux/module.h>
  
  #define INTR_STAT_OFS	0x0
  #define INTR_SET_OFS	0x8
  #define INTR_CLR_OFS	0x10
  
  #define MHU_LP_OFFSET	0x0
  #define MHU_HP_OFFSET	0x20
  #define MHU_SEC_OFFSET	0x200
  #define TX_REG_OFFSET	0x100
  
  #define MHU_CHANS	3
  
  struct mhu_link {
  	unsigned irq;
  	void __iomem *tx_reg;
  	void __iomem *rx_reg;
  };
  
  struct arm_mhu {
  	void __iomem *base;
  	struct mhu_link mlink[MHU_CHANS];
  	struct mbox_chan chan[MHU_CHANS];
  	struct mbox_controller mbox;
  };
  
  static irqreturn_t mhu_rx_interrupt(int irq, void *p)
  {
  	struct mbox_chan *chan = p;
  	struct mhu_link *mlink = chan->con_priv;
  	u32 val;
  
  	val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
  	if (!val)
  		return IRQ_NONE;
  
  	mbox_chan_received_data(chan, (void *)&val);
  
  	writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
  
  	return IRQ_HANDLED;
  }
  
  static bool mhu_last_tx_done(struct mbox_chan *chan)
  {
  	struct mhu_link *mlink = chan->con_priv;
  	u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
  
  	return (val == 0);
  }
  
  static int mhu_send_data(struct mbox_chan *chan, void *data)
  {
  	struct mhu_link *mlink = chan->con_priv;
  	u32 *arg = data;
  
  	writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);
  
  	return 0;
  }
  
  static int mhu_startup(struct mbox_chan *chan)
  {
  	struct mhu_link *mlink = chan->con_priv;
  	u32 val;
  	int ret;
  
  	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
  	writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
  
  	ret = request_irq(mlink->irq, mhu_rx_interrupt,
  			  IRQF_SHARED, "mhu_link", chan);
  	if (ret) {
  		dev_err(chan->mbox->dev,
  			"Unable to acquire IRQ %d\n", mlink->irq);
  		return ret;
  	}
  
  	return 0;
  }
  
  static void mhu_shutdown(struct mbox_chan *chan)
  {
  	struct mhu_link *mlink = chan->con_priv;
  
  	free_irq(mlink->irq, chan);
  }
  
  static const struct mbox_chan_ops mhu_ops = {
  	.send_data = mhu_send_data,
  	.startup = mhu_startup,
  	.shutdown = mhu_shutdown,
  	.last_tx_done = mhu_last_tx_done,
  };
  
  static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
  {
  	int i, err;
  	struct arm_mhu *mhu;
  	struct device *dev = &adev->dev;
  	int mhu_reg[MHU_CHANS] = {MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET};
  
  	if (!of_device_is_compatible(dev->of_node, "arm,mhu"))
  		return -ENODEV;
  
  	/* Allocate memory for device */
  	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
  	if (!mhu)
  		return -ENOMEM;
  
  	mhu->base = devm_ioremap_resource(dev, &adev->res);
  	if (IS_ERR(mhu->base)) {
  		dev_err(dev, "ioremap failed\n");
  		return PTR_ERR(mhu->base);
  	}
  
  	for (i = 0; i < MHU_CHANS; i++) {
  		mhu->chan[i].con_priv = &mhu->mlink[i];
  		mhu->mlink[i].irq = adev->irq[i];
  		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
  		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
  	}
  
  	mhu->mbox.dev = dev;
  	mhu->mbox.chans = &mhu->chan[0];
  	mhu->mbox.num_chans = MHU_CHANS;
  	mhu->mbox.ops = &mhu_ops;
  	mhu->mbox.txdone_irq = false;
  	mhu->mbox.txdone_poll = true;
  	mhu->mbox.txpoll_period = 1;
  
  	amba_set_drvdata(adev, mhu);
  
  	err = devm_mbox_controller_register(dev, &mhu->mbox);
  	if (err) {
  		dev_err(dev, "Failed to register mailboxes %d\n", err);
  		return err;
  	}
  
  	dev_info(dev, "ARM MHU Mailbox registered\n");
  	return 0;
  }
  
  static struct amba_id mhu_ids[] = {
  	{
  		.id	= 0x1bb098,
  		.mask	= 0xffffff,
  	},
  	{ 0, 0 },
  };
  MODULE_DEVICE_TABLE(amba, mhu_ids);
  
  static struct amba_driver arm_mhu_driver = {
  	.drv = {
  		.name	= "mhu",
  	},
  	.id_table	= mhu_ids,
  	.probe		= mhu_probe,
  };
  module_amba_driver(arm_mhu_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("ARM MHU Driver");
  MODULE_AUTHOR("Jassi Brar <jassisinghbrar@gmail.com>");
  